Burner tube assembly for heat treating furnaces



Feb. 11, 1958 H. N. IFSEN 2,822,798

BURNER TUBE ASSEMBLY FOR HEAT TREATING FURNACES Filed Oct. 19, 1953 2 SheetsvSheet 1 CfiT-roruosyf H. N. IPSEN 2,822,798

BURNER TUBE ASSEMBLY FOR HEAT TREATING FURNACES Feb. 11, 1958 2 Sheets-Sheet 2 Filed Oct. 19, 1953 mvlswfo ucwowd n. EE

United States Patent BURNER TUBE ASSEMBLY FOR HEAT TREATING FURNACES Harold N. Ipsen, Rockford, Ill. Application October 19, 1953, Serial No. 386,853

1 Claim. (Cl. 126-91) This invention relates to heat treating furnaces in which the furnace chamber is heated by tubes extending across the chamber. These tubes which often are made of a refractory material, are mounted on the furnace walls and the heat is derived by burning gas to produce a flame extending along the length of the tube on the inside thereof.

One object of the invention is to mount the heating tube on the furnace in an improved manner to simplify the overall construction, hold the tube in place and permit the tube to expand when heated.

A more detailed object is to seat one end of the tube on an annular shoulder and to hold the tube in place by means of a resilient bellows which is connected to the other end of the tube and yieldably urges the latter against the shoulder.

Other objects and advantages of the invention will become apparent from the following detailed description taken in connection with the accompanying drawings, in which Figure 1 is a transverse sectional view of a furnace employing heating tubes which are mounted in the novel manner provided by the present invention.

Fig. 2 is an enlarged fragmentary sectional view showing the manner of mounting one end of the tube.

Fig. 3 is an enlarged fragmentary sectional view illustrating the manner in which the other end of the tube is mounted.

As shown in the drawings for purposes of illustration, the invention is embodied in a heat treating furnace whose top, bottom and side walls, 11, 12 and 13 define a chamber 14 in which the workpieces (not shown) are placed for treatment. In furnaces of this type, the workpieces are disposed within a box-like baffie 15 which rests on blocks 16 on the bottom wall 12 of the furnace to be spaced from all of the furnace walls. To heat the chamber 14, heating elements such as the gas tubes 17 are disposed between the side walls of the baflle 15 and the furnace side walls 13 and extend vertically between the top and bottom walls 11 and 12. Herein, each tube is made of a refractory ceramic material and the end portions of the tube project into alined holes 18 and 19 in the top and bottom walls and are attached to these Walls. During treating of the workpieces, the atmosphere within the chamber 14 is circulated across the heating tubes and the workpieces by a fan 20 mounted on the lower end of a vertical shaft 21 which projects down through the top Wall 11 and is driven by a motor 22.

In accordance with the present invention, each heating tube 17 is mounted on the furnace walls 11 and 12 in a novel manner to hold the tube securely in place while permitting the tube to expand when heated and, at the same r 2,822,798 Patented. F cl). .1

time, to achieve a comparatively simple construction. For these purposes, one end of the tube is seated on an annular shoulder 23 which faces inwardly around the hole 19 and a resilient bellows 24 is attached to the wall 11 and yieldably engages the other end of the tube to urge -the latter against the shoulder. When using a ceramic tube, this arrangement has the additional advantage of placing the tube under compression only and thus minimizes the danger of the tube breaking.

In the present instance, the shoulder 23 is formed on the inner end of an annular casting 25 which projects into the outer end of the hole 19 in the bottom wall 12 and is held in place by bolts 26 projecting through a flange 27 on the casting and threaded into the wall. To provide a firm seat for the tube 17, an annular gasket 28 made of rubber or the like is placed on the shoulder 23 and the lower end of the tube rests on the gasket. To support the burner tip 29 of the tube, the tubular end 30 of the tip is pressed into an axial bore 31 of a cap 32 which is placed over the casting 23 and secured to the latter by bolts 33. The tip 29 is connected to a suitable supply of fuel gas through a nipple 34 on the cap.

At its upper end, the tube 17 projects up beyond the top wall 11 of the furnace and the projecting end portion 34 of the tube is encircled by the bellows 24. The latter preferably is made of yieldable metal and may be of the type sold under the trade name of Sylphon. A flange 35 around the lower end of the bellows is secured to the top wall 11 around the hole 18 by bolts 36, a gasket 37 being interposed between the flange and the wall. The upper end of the bellows is bent in around its entire periphery as indicated at 38 and this bent portion projects in over the upper end of the tube 17 so that the hole 18 is sealed closed around the tube to prevent escape. If desired, es-

cape of heat from the chamber 14 may further be pre vented by filling the bellows and the hole around the tube with an insulating material 39 such as a heat resistant fibre.

To hold the tube 17 in place, the bellows 24 is stretched initially to serve as a contractile spring and urge the tube down against the shoulder 23. As the tube is heated, it expands, this being permitted by the bellows which stretches further to permit such expansion. Thus, whether the tube is hot or cold, the bellows effectively holds it on its seat 23.

It will be observed that, with the present invention, the tube 17 is mounted in the furnace simply by attaching the annular casting 25 and the bellows 24 to the walls 12 and 11 of the furnace. In addition to being simple and inexpensive, therefore, this construction permits the tube to be removed quickly and easily for repair or replacement. At the same time, the tube is held firmly in place and is free to expand when heated. Should a ceramic tube be used, it is held only in compression and the danger of the tube being broken thus is reduced.

I claim as my invention:

A furnace having, in combination, a walled enclosure defining a chamber, two opposed walls of said enclosure having alined holes extending therethrough and opening into said chamber, a rigid annular member attached to one of said walls with its opening coaxial with a hole therein and having an annular shoulder concentric with the opening and facing inwardly of said enclosure, an elongated heating tube having one end loosely seated on said shoulder and projecting across said chamber and through the hole in the other of said walls with the opposite end portion of the tube disposed exteriorly of the latter wall, a bellows surrounding and extending along said tube end portion with one end connected to the outer end of the tube, means detachably securing the other end of said bellows to said other Wall, said bellows being stressed to hold said tube against said shoulder, a burner tip projecting through the opening in said member and into said tube, and means for detachably securing said burner tip to said member.

References Cited in the file of this patent UNITED STATES PATENTS 4 Udell Sept. 8, Wilson Mar. 27, Hepburn et al July 14, Wilson Nov. 22, Woods-on Nov. 22, Vaughan Aug. 26, Stookey June 7, Weaver May 27, Herbster Oct. 13,

FOREIGN PATENTS Great Britain June 7, Great Britain June 21, Switzerland Dec. 17, 

